本项目需要把数据存档位二进制文件,载入时只载入文件索引，通过索引，快速定位到数据内容，从而实现最小存储，最快速查找。下面代码是初步实现，通过扩展，还实现搜索引擎关键字匹配度，权重，分词效果，这是后话，先把最基础的通过偏移量快速查找分享下。

 

/// 
    /// 索引文件结构    /// 
    struct Token    {        /// 
        /// 关键字        /// 
        public string ID;        /// 
        /// 移偏量        /// 
        public int Offset;        /// 
        /// 长度        /// 
        public int Length;    }

　　

/// 
    /// 搜索    /// 
    class Search    {        private static StringBuilder _mainContent = new StringBuilder();        //生成索引文件和数据文件        public void BuildFile()        {            //生成索引文件            if (File.Exists("index.txt"))                File.Delete("index.txt");            using (FileStream aFile = new FileStream("index.txt", FileMode.Append, FileAccess.Write, FileShare.ReadWrite))            {                Random rd = new Random();                int rdv = 0;                byte[] bytes = null;                byte[] byCont = null;                int offset = 0;                int len = 0;                using (BinaryWriter bw = new BinaryWriter(aFile, Encoding.UTF8))                {                    for (int i = 0; i < 15; i++)                    {                        rdv = rd.Next(10, 305000);                        string indexerid = string.Empty;                        indexerid = i.ToString() + DateTime.Today.ToString("yyyyMMdd");                        _mainContent.Append(indexerid + "|test programe" + rdv.ToString());                        string result = indexerid + "|test programe" + rdv.ToString();                        bytes = System.Text.Encoding.UTF8.GetBytes(_mainContent.ToString()); //所有内容                        byCont = System.Text.Encoding.UTF8.GetBytes(result);  //本次内容                        //计算偏移量和内容长度                        if (i == 0)                        {                            offset = 0;                            len = byCont.Length;                        }                        else                        {                            offset = bytes.Length - byCont.Length;                            len = byCont.Length;                        }                        bw.Write(indexerid + "," + (offset) + "," + (len));                        bw.Flush();                    }                }            }            //生成数据文件            if (File.Exists("data.txt"))                File.Delete("data.txt");            using (FileStream dFile = new FileStream("data.txt", FileMode.Append, FileAccess.Write, FileShare.ReadWrite))            {                Random rd = new Random();                byte[] bytes = null;                using (BinaryWriter bw = new BinaryWriter(dFile, Encoding.UTF8))                {                    bytes = System.Text.Encoding.Default.GetBytes(_mainContent.ToString());                    bw.Write(_mainContent.ToString());                    bw.Flush();                }            }        }　　　　　//加载索引表到内存        public Dictionary
     
       GetTokenDic()        {            Dictionary
      
        dic = new Dictionary
       
        ();            using (FileStream aFile = new FileStream("index.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite))            {                using (BinaryReader bw = new BinaryReader(aFile, Encoding.UTF8))                {                    for (int i = 0; i < 15; i++)                    {                        string result = bw.ReadString();                        if (result.IndexOf(',') != -1)                        {                            string[] arr = result.Split(',');                            Token token = new Token();                            token.ID = arr[0];                            token.Length = Convert.ToInt32(arr[2]);                            token.Offset = Convert.ToInt32(arr[1]);                            dic.Add(arr[0], token);                        }                    }                }            }            return dic;        }        //根据关键字，通过偏移量快速查找内容        public void ReadFile(string key)        {            Dictionary
        
          dic = GetTokenDic();            //char[] charData = null;            FileStream file = new FileStream("data.txt", FileMode.Open);            int dOffset = 0;            int dLen = 0;            Token t = new Token();            if (dic.TryGetValue(key, out t))            {                dOffset = t.Offset;                dLen = t.Length;            }            byte[] byData = new byte[dLen];            using (BinaryReader bw = new BinaryReader(file, Encoding.UTF8))            {                file.Seek(dOffset + 2, SeekOrigin.Begin);                                file.Read(byData, 0, dLen);                 string d = Encoding.UTF8.GetString(byData);                Console.WriteLine(d);                file.Close();            }        }    }
        
       
      
     

　　

static void Main(string[] args)        {            Search s = new Search();            //s.BuildFile();            s.ReadFile("1420130825");            Console.Read();        }